The present invention relates to an analog-to-digital converting apparatus having an automatic gain control circuit comprising an analog gain controllable amplifier and an analog-to-digital (A/D) converter coupled to an output of the analog amplifier, a gain control loop of said analog amplifier receiving output signals from the A/D converter.
Such an analog-to-digital converting apparatus is known from the French Patent Application No. 2 536 620 (RCA Corp.), which corresponds to U.S. Pat. No. 4,517,586. Herein, the values of the digital samples from the A/D converter are digitally compared to a reference level, in order to produce a digital difference signal which is converted by a digital-to-analog converter into an analog gain control signal of the gain controllable amplifier. This solution leads to a complicated and thus costly circuitry.